ISOPODS OF NORTH AMERICA. 439 



longer. Last segment of fiagellum with a spine more than twice 

 length of segment, beside which there is an olfactory club two-thirds 

 as long; another somewhat shorter olfactory club on penultimate 

 segment. Last segment of the basal portion of the inner antennae 

 provided with three spines, as in C. stygia. Outer antennae probably 

 as long as body. Basal portion of five segments, the first three short 

 and thick, the fourth and fifth much longer and more slender. The 

 flagellum consists of at least forty segments. Mouth parts essentially 

 as those of C. stygia. Legs long and slender, first pair subchelate, 

 remaining ones with a weak claw. Inferior margin of the body seg- 

 ments beset with short spines. Size, very small, probably not over 

 3 mm. in length. Color, white. 



'"Habitat. Subterranean stream near San Marcos, Texas. Collected 

 by Dr. C. H. Eigenmann, from the U. S. Fish Commission well. 



"The above description is from a fragment. The telson and caudal 

 appendages were gone, also part of the outer antennae. The writer 

 hopes soon to receive the material which will enable him to fill out the 

 gaps in the above diagnosis. 



"In honor of Dr. H. M. Smith, in charge of scientific inquiry of 

 the U. S. Fish Commission." C. J. ULRICH/' 



Family XVI. STENETRIID^. 6 



Eyes present, large, sub-dorsal. Body depressed, elongate. 



First pair of antennas with flagellum composed of several articles. 

 Second pair of antennae with multi-articulate fiagellum. 



Mandibles with palp. 



Lateral margins of thorax but little produced, not laciniate. First 

 pair of legs in both sexes subcheliform; following pairs ambulatory, 

 with dactylus bi-unguiculate. 



Scale present outside of third joint of peduncle of second antenna?. 



First pair of pleopoda in female with appendages fused to form a 

 small operculum. Second pair wanting. Third pair with the outer 

 branches large, and forming, with the corresponding lamella of the 

 opposite side, a sort of operculum. Fourth pair with two branches. 

 Fifth pair consisting of a single branch. 



First pair of pleopoda in male small, with the peduncles fused; 

 branches single. Second pair situated below and not coupled with the 

 first pair; branches attached to the distal part of the inner margin of 

 the peduncle; inner branch geniculate, with distal joint narrow and 

 without cavity in its obtuse end; outer branch very short, much 

 shorter than inner one, and unjointed. Third, fourth, and fifth pairs 

 similar to those of female. 



"Trans. Amer. Microscopical Soc., 24th annual meeting, 1902, p. 93. 

 6 See Hansen for characters of family, Proc. Zool. Soc. London, 1905, II, Pt. 2, 

 p. 315. 



